For the rails caps, I use a steel pick tool with an "L" shape on one end. Stick it under the outer bottom lip and GENTLY pull outwards to release cap from it's "lip". 50% chance you might break one since the plastic is so old. Will refer you to a guy who makes/sells replacement sets....if necessary. 3D printed maybe? I don't remember.

For the rails themselves....
http://www.vehicross.info/showthread...+removal+paint